Context on those Mason-Dixon polls...

From NBC's Domenico MontanaroSome might be interpreting the latest Mason-Dixon polls as showing weakness for Obama since he has not reached 50%.

It's true that the bad news for Obama in these polls is, as we wrote in First Read, that he hasn't reached 50%. But it should also be pointed out that Obama's position has actually gotten stronger -- when looking at the Mason-Dixon poll trendlines -- particularly in states like Colorado, Nevada and Virginia. In other states, movement has been negligible and within the margin of error.

In Colorado, Obama has gained five percentage points from the previous Mason-Dixon poll, Sept. 29-Oct. 1, when the candidates were tied at 44%. In the latest poll, Obama leads by five, 49%-44%.

In Nevada, Obama has gained 10 points since August, when McCain led by six, 47%-41%, and two points since their Oct. 8-9 poll. In the latest poll, Obama leads 47%-43%.

In Virginia, Obama has gained six percentage points since a Sept. 29-Oct. 1 poll that showed a three-point McCain lead, 48%-45%. In the latest poll, it's Obama who leads by three, 47%-44%.

As far as the overwhelming majority of the undecided voters being white, keep in mind that black and Hispanic/Latino voters have consistently favored Obama by wide margins in public polling and have already moved toward the Democratic nominee. In states like Missouri, for example, where the race is within the margin of error, black voters only made up 8% of the electorate, and Hispanics/Latinos 1% in 2004. In Colorado, blacks made up just 4% of the electorate in 2004 and Hispanics made up 8% in exit polls.

That doesn't mean that McCain might not have an advantage with remaining white voters, since he is winning a majority white voters generally in public polling and focus groups. But it is also telling that many undecideds are Bush voters and have not yet decided on McCain.

Here's what we wrote in First Thoughts for context:*** Good news and bad news: Our new map comes at the same time as the release of a final round of Mason-Dixon polls, and they contain both good news and bad news for the candidates. The numbers: Obama is ahead five points in Colorado (49%-44%), two in Florida (47%-45%), four in Nevada (47%-43%), and three points in Virginia (47%-44%). Meanwhile, McCain is up one in Missouri (47%-46%), three in North Carolina (49%-46%), and two in Ohio (47%-45%). The good news for Obama -- and bad news for McCain -- is that if Obama holds on to his leads in CO, FL, NV, and VA, he's going to easily win on Tuesday, racking up well over 300 electoral votes. But the bad news for Obama -- and good news for McCain -- is that Obama is below 50% in all of these polls. And if undecideds break decisively for McCain, that's how he would pull off the upset. But if the 2004 presidential contest taught us anything, it's that turnout sometimes is more important than undecided voters. In our final NBC/WSJ poll before the 2004 election, Bush held a one-point lead over Kerry, 48%-47%. And there was the assumption that undecideds breaking for the challenger over the incumbent would propel Kerry to victory. But that didn't happen. By the way, our final NBC/WSJ poll comes out first thing tomorrow morning.